A few months ago I recorded the sound of an adult bicycle with good success. Last week I decided to experiment with one of my dpa 4060's and Sony D100 recorder on my grandson's bike. I attached the mic with some putty just behind the pedals near the back tire. Thankfully, the cord to the 4060 is fairly long so I was able to run alongside him to get the recording. The trick was to keep it from picking up my shoes as I ran down the road and to keep him from going too fast! After three or four takes, I was able to get what I was after.
Here is a link to the sound: Riding Small Bicycle